It's amazing; it's only been two weeks when I started to pay attention to ACA Financial. Their share price took a big fall, dropping about 60% in just two days. Surprisingly, their share price marched back after that, regaining most their losses. I was checking every day for news, but there was nothing for about a week. Then they were delisted from the NYSE. But the poo-poo really hit the fan when they were rated down to junk status by S&P.
Since then, there has been enormous fall out. A lot of attention has been paid, because it turns out ACA was a small fish in the big pond of bond insurers. And the rotting corpse of ACA is starting to make all the other fish in the pond very sick. A Google news search pulls up TONS of articles, so feel free to look there for much more expert opinion than anything I can pull out of my amateur ass.
I'll do some looking, but you can't go wrong visiting Calculated Risk. They've been covering the most important developments, and the comment sections are usually worth reading. I'm a wanna-be finance guy; Calculated Risk is the real deal.